applications A & B Flashcards
medical genetics
focuses on diagnosis and management of medical, psychological, and social aspects of diseases involving the mutation or influence of genes
family focus of medical genetics
related to both medical care/management of patient and forward-looking consideration of future offspring
3 types of hereditary disease
- mendelian conditions
- chromosomal conditions
- multifactorial conditions
mendelian conditions
- caused by mutation of single gene
- autosomal dominant/recessive, X-linked dominant/recessive, Y-linked, mitochondrial
- inherited from one or both parents, or new mutation
chromosomal conditions
- extra chromosome, missing chromosome, duplication/deletion of segment, structural rearrangements
- developmental/physical abnormalities can result due to human sensitivity Gene Dosage
- autosomes or sex chromosomes
multifactorial conditions
- multiple genes and environmental factors
- increased likelihood = inherited susceptibility
- differing mutant allele frequencies
ex. of chromosomal condition
trisomy 21
ex. of multifactorial condition
diabetes
different types of testing for genetic conditions
- molecular analysis of DNA/RNA
- biochemical analysis
- chromosome analysis
molecular analysis tests
useful when suspicion of specific Mendelian condition
biochemical analysis
tests blood or tissues for absence or presence of certain proteins as well as levels
chromosome analysis
chromosomal causes of:
- fetal or infant malformations
- mental impairment/physical abnormalities
- long-term infertility in adults
carrier testing
identifies individuals who are heterozygous for recessive conditions or have chromosomal abnormality that could produce condition in future child
do carrier individuals who undergo carrier testing have the genetic condition?
no
ex. of carrier frequency being so high that carrier testing is a public health effort
Tay-Sachs disease in Ashkenazi Jewish populations
pre-symptomatic testing
used for genetic conditions with l ate age of onset
ex. of disease tested with pre-symptomatic testing
autosomal dominant Huntington disease
- by age 40, only about 50% of people show condition
newborn testing
consists of set of mandated genetic tests that together require only a few drops of blood from a “heel stick”
in 2003, the advisory committee established the ______________ ________________ ____________ that contained list of genetic disease recommended for testing
Recommended Uniform Screen Panel (RUSP)
what do nearly all states test for
34 “core” hereditary conditions
additional conditions that states might include testing for
25 “secondary” conditions
what is newborn genetic screening considered?
public policy intended to save lives, reduce medical costs, and support well-being of families
what do positive test results of genetic screening allow
immediate start of treatment
prenatal testing
performed during pregnancy to detect a condition in a fetus including chromosomal abnormalities and developmental defects
types of prenatal testing
- chorionic villus sampling (CVS)
- amniocentesis
- sometimes ultrasound
chromosome conditions are unlikely to be ________-
treatable
ex. of condition identified by prenatal testing
trisomy 21
what can prenatal testing trigger
ethical conflicts about keeping or terminating an affect pregnancy
amniocentesis
uses needle to penetrate uterus and placenta of pregnant woman to obtain amniotic fluid, which contains fetal cells
when is amniocentesis performed
obtains cells between 14th-18th week of pregnancy
danger of amniocentesis
risk of fetal loss
chorionic villus sampling (CVS)
small tube passed transvaginally into uterus to obtain tissue from the chorion (fetal derived portion) on the outside of the placenta
when is CVS performed
cells obtained as early as 10th week
is CVS or amniocentesis riskier
CVS
maternal serum screening
measures level of 3 proteins in pregnant woman’s blood between 15th-20th week of gestation
what are the proteins screened for in woman associated with
2 trisomy conditions and neural tube defect
is MSS screening or diagnostic
screening
how is screening test different from diagnostic test
it indicates increased likelihood of condition rather than presence of a condition
what are abnormal MSS results followed with
recommendation of amniocentesis or CVS
ultrasound
produces images of fetus that can be used to diagnoses certain conditions, such as neural tube defect and other developmental abnormalities
what can ultrasounds be used routinely for
accurate measurement of fetal age
- this can determine due date
fetal sex
if MSS suggests possibly Down syndrome, what may be recommended
karyotyping
fetal cell sorting
identifies and isolates fetal cells in maternal blood circulation for DNA and chromosome analysis
ex. of conditions identified by fetal cell sorting
cystic fibrosis and spinal muscular atrophy
preimplantation screening
tests for hereditary diseases in fertilized embryos produced by in-vitro fertilization
in vitro fertilization (IVF)
long-standing method of assisted reproduction for ind. and couples
- expensive, not usually covered by insurance
process of in vitro fertilization
- ovulation induced in woman using hormone injections
- eggs removed for surface of ovaries
- eggs stored or used immediately for fertilization
- fertilized eggs implanted in uterus
why might fertilized eggs have one cell removed?
for preimplantation screening using PCR to identify recessive genetic conditions when parents are normal carriers
success rates of in vitro fertilization
15-40%, depending on age of woman
direct to consumer testing is run by what kind of company?
for-profit comapnies
what does direct to consumer testing often duplicate
medically available genetic carrier testing
various types of direct to consumer testing offered
- ancestry
- carrier status
- drug response
- likelihood of certain physical traits
what did the US Food and Drug Administration approve in April 2017?
genetic testing by 23&Me to indetify individual’s risk of developing 10 medical conditions influence by genetics
individuals more likely to carry the 10 medical conditions carry certain what?
single nucleotide polymorphism (SNP) variants
do SNP markers cause or show association with the conditions?
show association
public health concerns with direct to consumer genetic testing
- how genetic counseling and medical monitoring will be accessed, paid for, and managed
- view of ourselves that was unavailable in previous generations
Ethical , Legal, and Social Implications (ELSI) purpose
- examine design/conduct of GENETIC RESEARCH
- studying use/influence of GENETIC HEALTH CARE
- investigation of SOCIETAL ISSUES
- examine impact of legal, regulatory, and public POLICIES
Genetic Information Nondiscrimination Act (GINA) of 2008
severely restricts use of personal genetic information in issuing health insurance and life insurance, and in employment decisions
Affordable Care Act (ACA) of 2010
excludes use of personal genetic information in issuing health insurance as part of clause preventing use of preexisting conditions as basis for rejection
